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what is the minimum current sinking capability for pic16f18854? also i need to connect input switch to the pic.i have tried making my own and assuimg suitable data.please help me is this correct.need your suggestion.thank you

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    \$\begingroup\$ What does the datasheet say? \$\endgroup\$ – Colin Mar 31 '18 at 6:11
  • \$\begingroup\$ Data sheet mentions only the maximum current i/o i.e 50 milli amps.here i don't know the minimum current since i need to take care of power dissipation.thank you \$\endgroup\$ – Ali Lightwala Mar 31 '18 at 6:57

The inputs are MOSFET gates, they need very little current to sense the voltage. a few microamperes perhaps.

your circuit looks good.

Unless you need speed I'd use larger resistors like 100K and 86K if this is for an automible application. because a load dump could put 80V or more where you have 12V written and you'll be relying on the protection diodes in the PIC to protect the input.

  • \$\begingroup\$ thank you so much for ur valuable answer.the one u are talking about the 12V,there i will be connecting simple button.And the load will be connecting to another output pin using some driver circuit..and it is nothing to with the 12v. am i right comment on this.thank you \$\endgroup\$ – Ali Lightwala Mar 31 '18 at 7:03
  • \$\begingroup\$ load dump is an automobile phenomon related to the way alternators, batteries, and motors operate. if it's not going to be connected to an automobile ignore that comment... I understand that will be powering the PIC with a lower voltage like 5V or 3V \$\endgroup\$ – Jasen Mar 31 '18 at 7:15
  • \$\begingroup\$ actually u reached to my project, in need to control the gate which has a ac induction motor.let me make it clear,in general i need to control the gate meaning need to drive motor in reverse and forward direction.so i am trying to connect 2 button one for forward direction and other for reverse direction.this is it.am using transistors to drive the relay and motor forward and backward. \$\endgroup\$ – Ali Lightwala Mar 31 '18 at 7:24
  • \$\begingroup\$ the voltage divider which i have drawn and posted is it correct? if yes then please tell me how will i calculate the power of each resistor. \$\endgroup\$ – Ali Lightwala Mar 31 '18 at 7:29
  • \$\begingroup\$ it looks correct, I didn't go into the full aritmetic, but by mental approximation I would expect just under 5V , how precise are your resistors? \$\endgroup\$ – Jasen Mar 31 '18 at 7:52

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